Multi-energy type X-ray CT apparatuses are for scanning an object to be examined by two or more different energy spectra while rotating one or more X-ray sources and one or more X-ray detectors that are disposed facing each other placing the object therebetween and irradiating X-rays to the object, and generating tomograms (tomographic images) using the X-ray transmission data acquired from the scanning (refer to Patent Document 1 for more details).
In multi-energy type X-ray CT apparatus, by scanning using two or more different energy spectra and calculating difference thereof, etc., an identification tissue that is desired to be identified on the tomographic image and a separate tissue that is in the background of the identification tissue can be displayed with enhanced contrast considering energy dependency of X-ray attenuation characteristics of the tissues thereof, which provides an advantage that the identification tissue can be easily identified (identification ability is higher and the desired identification tissue can be easily found by a radiogram interpreter).
Patent Document 1: JP-A-2004-174253